Date: Wed, 2 Nov 2016 14:24:43 -0500 From: Eric van Gyzen <vangyzen@FreeBSD.org> To: "current@freebsd.org" <current@freebsd.org> Subject: copyinstr and ENAMETOOLONG Message-ID: <236b8c7c-a12e-0872-f3cb-03f99bb5fcc5@FreeBSD.org>
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Does copyinstr guarantee that it has filled the output buffer when it
returns ENAMETOOLONG? I usually try to answer my own questions, but I
don't speak many dialects of assembly. :)
I ask because I'd like to make the following change, and I'd like to
know whether I should zero the buffer before calling copyinstr to ensure
that I don't set the thread's name to the garbage that was on the stack.
Eric
Index: kern_thr.c
===================================================================
--- kern_thr.c (revision 308217)
+++ kern_thr.c (working copy)
@@ -580,8 +580,13 @@ sys_thr_set_name(struct thread *td, struct thr_set
if (uap->name != NULL) {
error = copyinstr(uap->name, name, sizeof(name),
NULL);
- if (error)
- return (error);
+ if (error) {
+ if (error == ENAMETOOLONG) {
+ name[sizeof(name) - 1] = '\0';
+ } else {
+ return (error);
+ }
+ }
}
p = td->td_proc;
ttd = tdfind((lwpid_t)uap->id, p->p_pid);
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